Can I just offer you my love and compassion? It is excruciating to have to lay eyes on one who so deeply hurt the one you most love. It takes superhuman strength to not strike out in defense of your beloved. The advice given above is valid, though you already knew that.
The advice I most like is WestChesterguy's:
i don't suggest one way or another. however, if i were in the husband's shoes - knowing my wife is an independent thinker and lady of action - whatever she did or does is up to her. the consequences are also up to her to handle as well.
if she confronted the perpetrator - that would be her thing. i would go about my business of recovery and whatever. and while i may not tell my wife what i think about her confrontation. i'd probably smile when she wasn't looking....
This is your problem, too. This is your family, too. That being said, your first allegiance is to your husband's wishes. Maybe he would be well-served in having you defend the little boy who was defenseless? Or maybe he would feel re-victimized at having to deal with the confrontation?
If he doesn't feel strongly one way or the other, I say to your own self be true.
But remember, words once spoken, can't be taken back.
Talk to your husband about your feelings. Just knowing how strongly you want to defend him is a great validation of your love. And who could not want that?
Praying for wisdom for you!